In 1861, he became an apprentice to a cameo-cutter, Louis Avet, and took evening art classes at the Cooper Union in New York City. Two years later, he was hired as an apprentice of Jules Le Brethon, another cameo cutter, and enrolled at the National Academy of Design. At age 19, his apprenticeship was completed and he traveled to Paris in 1867, where he studied in the atelier of François Jouffroy at the École des Beaux-Arts.

In 1870, he left Paris for Rome to study art and architecture, and worked on his first commissions. There he met a deaf American art student, Augusta Fisher Homer, whom he married on June 1, 1877. The couple had one child, a son named Homer Saint-Gaudens.

In 1874, Edwards Pierrepont, a prominent New York reformer, hired Saint-Gaudens to create a marble bust of himself. Pierrepont, a phrenologist, proved to be a demanding client, insisting that Saint-Gaudens make his head larger. Saint-Gaudens said that Pierrepont’s bust “seemed to be affected with some dreadful swelling disease” and he later told a friend that he would “give anything to get hold of that bust and smash it to atoms”.

In 1876, he won a commission for a bronze David Farragut Memorial which Richard Gilder modeled the legs for.